Kekek-

Did you find that changing your damping helped the car rotate any better. I found that on my last run in DC reducing the rebound up front helped the front grip better. The rear end is still a mystery to me since I am running significantly higher rates than the stock KW's. After I mess with damping a bit more I may go up in rear rate as well. I feel like I need the car to be a LOT looser.

 

I'm really finding that the rear just has TONS of grip. I tried dropping the rear 1/2", no help there. I tried adding more static toe out, no help there. Looks like I'll drop rear camber to about -1.5 and run about 1/8" toe out with the stock type toe link bushing. This kicked *** last year, but don't try it unless you drive with the throttle (lots of modulation, no snapping off on corner entry!).

 

Huh, I wouldn't have thought the bump steer kit would induce understeer. I have mine sitting in my shop waiting to go in but, now I may hold off.

 

My rear camber is -1.5 and my rear ride height is good. I may try another 100lbs in spring before I toe out too much. I still drive my car on the street so I don't want to have it crazy loose. (or maybe I do )

 

Wow, interesting to hear that opinion. Russ, what dont you like about the rear bump steer kit? Same as kekek or different/additional issue(s)?

 

Basically my opinion is that it may "bind" the suspension just enough to where it loses that "fluid" feel. To me it feels like it's not predictable when you initially lean on it, meaning sometimes the rear end gives up enough like it should and sometimes it doesn't. I'm on JIC coilovers with 550 lb springs up front and 700 lbs. in the rear with a 27mm rear sway bar. -1.5 camber in the rear with a 1/8th of toe out. I may pick up some extra toe links from a salvage yard and swap them out just get a feel for the difference.

 

Russ-

How do you find your rotation in sweepers with the 550/700 setup? Did you do it with a stock rear bar before you installed the 27mm? I want the rotation but I want to keep the stock rear bar to avoid inside rear tire lift.

 

Rear bar def is not necessary Dave. If you look at the Warminster results from a couple weeks ago GJ Dixon drove an STU car with one of my old setups with OTS Tein RA's and 10/12 spring rates and stock bars. He almost had top pax and was faster than both Corey and Dan. I think toe out and less camber is the best route to keep the rear end "loose".

 

Keep in mind, I'm tuning for the open diff in front but the 27 mm rear bar only helped with corner exit. Last year I ran 650 lb. rear springs and the rotation was okay but not good. With 700 lb. springs its better, I don't have to run crazy rear pressures this year. To try and minimize the tripod mode, I run lower but closer to the stock rake front to rear.

 

Just curious, what is the downside to a car lifting the inside rear tire? I mean that tire is completely unloaded at that point anyway.

 

The running theory is that when the car goes to tripod mode, it's hurting corner exit because you're only getting 3 wheels driving the car out of the corner instead of 4. Personally, I'm not in that camp because even if all four wheels were on the ground, you still wouldn't get the drive out because of the cornering state the car is in.

My bigger reason for running stock rake is to get the weight transferred to the rear a little easier.

 

If the problem is that the car is pushing on corner exit, then wouldn't increasing the rear contact patch make it push even more?

 

What about a bigger front bar to help eliminate the tri-pod effect??? I love my Whiteline (26mm) FSB.

Dennis

 

This isn't theory. It's reality - perhaps just not something you've personally observed.

Unless you have a rear diff that is as efficient putting down power with one wheel in the air as it is with both on the ground, then you're loosing power on corner exit with one in the air. Combine this with a center diff that is similar and you're possibly loosing A LOT of power - enough to effectively "stall" the car mid-corner, wind up that inside rear, and then unsettle the balance of the chassis as it touches back down on the pavement.

This typically isn't a significant problem on ST* cars (unless too softly sprung...), but is on R-tired and slick-shod cars. For tricycle action, just watch the E Prepared Civics. The point, however, is that both their drive wheels (front) are still on the ground.

At various stages of development of my Impreza I've experienced inside rear lift (STS), inside front lift (DSP) and have bicycled through corners (in F Prepared on slicks). In all cases, regardless of the differentials on the car, power loss was an issue.

To sum up, keeping inside rear lift manageable is important, tough totally eliminating it isn't possible in all conditions.

 

Just to add to the inside tire lift thing. Lift on corner entry is not a bad thing - just as long as it gets seated again mid corner. Its expected to lift with a big rear bar on entry as your yaw rate increases rapidly (yaw acceleration?). If you have enough front grip (and not too much caster to jack the front end) the front end will not push on entry. Mid corner you should start to be back on the gas and the inside rear should come back down - but the closer you can keep it the less it has to travel when you get on the gas and therefore the more power that ends up propelling the car.


Ninja edit - not only when do you have trouble putting power down with a tire in the air - but you are losing roll stiffness too. The total stiffness of the axle pair is going to depend on your ride rate - anti-roll bars only work when something is pushing on the opposite end of the bar. If one end is in the air - its just like disconnecting an endlink. So as soon as you lift a tire - your front roll stiffness becomes mucho higher than the rear and then you get push. Its all a delicate balance. There is no right answer to this problem because a lot of it is less dependent on the actual position of the suspension and rather on the velocity and acceleration of mass.